In various surgical procedures, one implant can be secured relative to another implant and/or to an anatomical structure. For example, spinal fixation procedures can be performed to align and/or fix desired relationships between adjacent vertebrae and can utilize multiple implants. Spinal fixation procedures typically include positioning a plurality of spinal fixation assemblies within target vertebrae, each fixation device typically having a threaded shank portion configured to be disposed (e.g., threaded) within a vertebra and a proximal receiver head configured to receive and secure some type of spinal stabilization element (e.g., a rigid or flexible rod, a cable, a biological construct, a tether, a tape, etc.). Once these assemblies are disposed within the target vertebrae, a spinal stabilization element or rod can be positioned and secured within the receiver heads such as by rotating a driver to fix a locking element within the receiver head. Once secured as such, the installed spinal stabilization rod can hold the vertebrae in the desired spatial relationship, either until desired healing or spinal fusion has taken place, or for some longer period of time.
While a driver can be configured to advance the locking element within the receiver head, fixing the stabilization element therein, a user can encounter some difficulties. For example, when using a driver, it can be difficult to apply the rotational forces to the implant rather than to the anatomy. As the driver is rotated to advance the locking element in a receiver member of a fixation assembly, the locking element resists and the driver can unintentionally apply a force that tends to rotate the target vertebrae rather than rotate the locking element into and relative to the receiver member. During rotation of the implant, a counter torque can be applied relative to the implant to avoid this undesirable rotational force being applied to the vertebrae and instead apply the rotational force to the implant so that it can rotate relative to one or more other implants.
Conventional drivers can include counter torque features, but also have various deficiencies. For example, some drivers utilize first and second handles that are angularly offset and obstruct the view of the implant. In one such device, the first handle can be coupled to a sleeve and the second handle can be coupled to a shaft received in the sleeve such that rotating the shaft within the sleeve drives the implant. However, this configuration increases the size of the sleeve's diameter because it must be large enough to accommodate the shaft. This can make it difficult for a user to visually monitor the driving progress and can increase trauma by requiring larger incisions to accommodate the driver. Additionally, a user must use both hands to operate the driver, crowding the operating space and leaving the user with no free hands. Still further, if the distal end of the driver is offset from and improperly aligned with a mating feature formed in the screw, rotating the driver may strip the screw head and the screw must be removed and replaced before the procedure can continue, thereby increasing the duration of the surgical procedure and the associated risks to the patient.
Thus, there remains a need for surgical devices and methods for driving an implant and applying counter torque.